var Base64=function() {}
Base64.prototype.keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
Base64.prototype.encode = function (input) {
       input = escape(input);
       var output = "";
       var chr1, chr2, chr3 = "";
       var enc1, enc2, enc3, enc4 = "";
       var i = 0;
       do {
          chr1 = input.charCodeAt(i++);
          chr2 = input.charCodeAt(i++);
          chr3 = input.charCodeAt(i++);
          enc1 = chr1 >> 2;
          enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
          enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
          enc4 = chr3 & 63;
          if (isNaN(chr2)) {
             enc3 = enc4 = 64;
          } else if (isNaN(chr3)) {
             enc4 = 64;
          }
          output = output +
             this.keyStr.charAt(enc1) +
             this.keyStr.charAt(enc2) +
             this.keyStr.charAt(enc3) +
             this.keyStr.charAt(enc4);
          chr1 = chr2 = chr3 = "";
          enc1 = enc2 = enc3 = enc4 = "";
       } while (i < input.length);
       return output;
    }
Base64.prototype.decode=function (input) {
       var output = "";
       var chr1, chr2, chr3 = "";
       var enc1, enc2, enc3, enc4 = "";
       var i = 0;
       // remove all characters that are not A-Z, a-z, 0-9, +, /, or =
       var base64test = /[^A-Za-z0-9\+\/\=]/g;
       if (base64test.exec(input)) {
          alert("There were invalid base64 characters in the input text.\n" +
                "Valid base64 characters are A-Z, a-z, 0-9, '+', '/', and '='\n" +
                "Expect errors in decoding.");
       }
       input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");
       do {
          enc1 = this.keyStr.indexOf(input.charAt(i++));
          enc2 = this.keyStr.indexOf(input.charAt(i++));
          enc3 = this.keyStr.indexOf(input.charAt(i++));
          enc4 = this.keyStr.indexOf(input.charAt(i++));
          chr1 = (enc1 << 2) | (enc2 >> 4);
          chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
          chr3 = ((enc3 & 3) << 6) | enc4;
          output = output + String.fromCharCode(chr1);
          if (enc3 != 64) {
             output = output + String.fromCharCode(chr2);
          }
          if (enc4 != 64) {
             output = output + String.fromCharCode(chr3);
          }
          chr1 = chr2 = chr3 = "";
          enc1 = enc2 = enc3 = enc4 = "";
       } while (i < input.length);
       return unescape(output);
    }